Low-dust products using microcrystalline wax emulsion

ABSTRACT

The present invention relates generally to wall repair compounds such as joint compounds, spackling compounds, and the like used to repair imperfections in walls or fill joints between adjacent wallboard panels. Particularly, the present invention relates to such a wall repair compound comprising a dust reducing additive that reduces the quantity of airborne dust generated when the hardened compound is sanded. The dust reducing additive also imparts adhesion to the wall repair compounds to which it is added, for example to a joint compound. The dust reducing additive comprises microcrystalline-wax based emulsion.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is continuation of U.S. application Ser. No.15/274,258, filed Sep. 23, 2016, which claims the benefit from U.S.Provisional Application No. 62/232,032, filed on Sep. 24, 2015 thecontents of which are hereby incorporated by reference as if set forthin its entirety herein.

TECHNICAL FIELD

The present invention relates generally to wall repair compounds such asjoint compounds, spackling compounds, and the like used to repairimperfections in walls or fill joints between adjacent wallboard panels.Particularly, the present invention relates to such a wall repaircompound comprising a dust reducing additive that reduces the quantityof airborne dust generated when the hardened compound is sanded. Thedust reducing additive also imparts adhesion to the wall repaircompounds to which it is added, for example to a joint compound. Thedust reducing additive comprises microcrystalline-wax based emulsion.

BACKGROUND

Interior walls of residential and commercial buildings are oftenconstructed using gypsum wallboard panels, often referred to simply as“wallboard” or “drywall.” The wallboard panels are attached to studsusing nails or other fasteners, and the joints between adjacentwallboard panels are filled using a specially formulated adhesivecomposition called joint compound to conceal the joints.

The procedure for concealing the joint between adjacent wallboards, andthereby producing a smooth seamless wall surface, typically includesapplying soft, wet, joint compound within the joint or seam formed bythe abutting edges of adjacent wallboard panels using a trowel or thelike. A fiberglass, cloth, or paper reinforcing tape material is thenembedded within the wet joint compound, and the compound is allowed toharden. After the joint compound has hardened, a second layer of jointcompound is applied over the joint and tape to completely fill the jointand provide a smooth surface. This layer is also allowed to harden. Uponhardening, the joint compound is sanded smooth to eliminate surfaceirregularities. Paint or a wall covering, such as wall paper, can thenbe applied over the joint compound so that the joint and the drywallcompound are imperceptible under the paint or wall covering. The samejoint compound can also be used to conceal defects caused by the nailsor screws used to affix the wallboard panels to the studs, or to repairother imperfections in the wallboard panels, so as to impart acontinuously smooth appearance to the wall surface.

Various drywall joint compounds are known for concealing joints betweenadjacent wallboard panels. Conventional joint compounds typicallyinclude a filler material and a binder. Conventional fillers are calciumcarbonate and calcium sulfate dihydrate (gypsum), which are used in“ready mixed” joint compounds, and calcium sulfate hemihydrate(CaSO4-½H2O; also referred to as plaster-of-Paris or calcined gypsum),which is used in “setting type” joint compounds. Ready mixed jointcompounds, which are also referred to as pre-mixed or drying type jointcompounds, are pre-mixed with water during manufacturing and requirelittle or no addition of water at the job site. Such joint compoundsharden when the water evaporates and the compound dries. Setting typejoint compounds, on the other hand, harden upon being mixed with water,thereby causing dihydrate crystals to form and interlock. Setting typejoint compounds are therefore typically supplied to the job site in theform of a dry powder to which the user then adds a sufficient amount ofwater to give the compound a suitable consistency.

The Koltisko, Jr. et al. U.S. Pat. No. 4,972,013 provides an example ofa readymixed (wet) joint compound including a filler, binder, thickener,non-leveling agent, and water. The McInnis U.S. Pat. No. 5,277,712provides an example of a setting (dry mix-type) joint compound includinga fine plaster material, such as stucco (a material which impartsinternal strength) and methyl cellulose (which provides workability andwater retention) to the joint compound. Additional examples of jointcompounds are provided in the Brown U.S. Pat. No. 4,294,622; the MuddU.S. Pat. No. 4,370,167; the Williams U.S. Pat. No. 4,454,267; theStruss et al. U.S. Pat. No. 4,686,253; the Attard et al. U.S. Pat. No.5,336,318; and the U.S. Pat. No. 5,779,786.

A spackling compound is disclosed in the Deer et al. U.S. Pat. No.4,391,648. While joint compound and spackling compound do many of thesame things and are both smeared onto walls to hide flaws, spacklingcompound is generally lighter, dries more quickly, sands more easily,and is more expensive than joint compound. For simplicity, jointcompound, drywall joint compound, and like expressions are usedthroughout this specification to refer to wall repair compoundsgenerally, including joint compound and spackling compound.

Sanding hardened joint compound can be accomplished using conventionaltechniques including power sanders, abrasive screens, or manual sanderswhich consist simply of a supporting block and a piece of abrasive papermounted on the block. Sanding the joint compound, however, produces alarge quantity of an extremely fine powder which tends to becomesuspended in air for a long period of time. The airborne particlessettle on everything in the vicinity of the sanding site and usuallyrequire several cleanings before they can all be collected, therebymaking cleanup a time consuming and tedious process. The particles mayalso present a serious health hazard to the worker.

The airborne particles are highly pervasive and can enter the nose,lungs, eyes and even the pores of the skin. Results from a studyconducted by the National Institute for Occupational Safety and Healthfound that dust levels in 9 out of 10 test samples taken at test siteswhere workers were finishing drywall with joint compound were higherthan the limits set by OSHA. The report also said that the dust may notbe safe even when it falls within the recommended limits. In addition,the study found that several dust samples contained silica and kaolin,material founds in clay that have been found to cause permanent lungdamage. The report recommended the use of local exhaust ventilation, wetfinishing techniques, and personal protective equipment to reduce thehazard.

In an effort to reduce the dust generation and cleanup problemsassociated with the sanding of conventional joint compounds, variousattempts have been made to develop specialized dustless drywall sanders.The Matechuk U.S. Pat. No. 4,782,632, for example, discloses a drywallsander including a sanding head designed to minimize the release of dustand further discloses attaching a vacuum cleaner to the sanding head tocollect the dust. The Krumholz U.S. Pat. No. 4,955,748 discloses adustless drywall finisher which uses a wet sponge to prevent theformation of airborne dust.

Dust remains a problem, however, when conventional power sanders or handsanders are used to sand conventional joint compounds. A need thereforeexists for a joint compound that can be sanded using conventionalsanders without producing a large quantity of fine particles capable ofbecoming suspended in air. It would also be desirable to provide anadditive that could be mixed with commercially available joint compoundsto inhibit the formation of airborne particles during the sandingprocedure without otherwise interfering with the properties of the jointcompound.

The composition of the present invention addresses the above discussedproblems of dust generation. The emulsion of the present inventioncomprising colloidally-protected, microcrystalline-wax-basedmicrostructure can be added to a wall repair com-pound, for example, ajoint compound to serve as a dust reducing additive.

SUMMARY

The following presents a simplified summary of one or more aspects inorder to provide a basic understanding of such aspects. This summary isnot an extensive overview of all contemplated aspects, and is intendedto neither identify key or critical elements of all aspects nordelineate the scope of any or all aspects. Its sole purpose is topresent some concepts of one or more aspects in a simplified form as aprelude to the more detailed description that is presented later.

The present invention provides a wall repair compound, such as a jointcompound or spackling compound which, when sanded, generates a lowerlevel of airborne particles than conventional joint compounds. Inaddition, the joint compound of the present invention is also waterresistant and has excellent adhesive properties.

More specifically, the present invention provides a wall repair compoundwhich includes a dust-reduction additive. Generally, the wall repair orjoint compound includes a sufficient amount of the dust-reductionadditive so that when the joint compound is tested as described in thisspecification, it generates a lower quantity of airborne dust than thejoint compound would produce if it did not contain the dust-reductionadditive.

Disclosed herein are embodiments of a low-dust joint compound which cancomprise water, preservative, and dust-reduction additive (“DRA”), whichis a wax emulsion comprising colloidally-protectedmicrocrystalline-wax-based (“CMWB”) microstructures. The DRA can bepre-mixed into the wet joint compound prior to application. Generally,the dustreduction additive reduces the quantity of airborne dustparticles having a size of less than or equal to 10 microns to less than50% of the quantity that would be generated without the additive. Incertain embodiments, the quantity of airborne dust particles is reducedby at least 75% compared to a mixture without the additive. Mostpreferably, the level of airborne dust is reduced by more than 90%. Inone embodiment, the quantity of airborne particles generated by sandingthe hardened joint compound of the present invention was less than 50mg/m3 and, in certain other embodiments, less than about 20 mg/m3. Thequantity of airborne particles generated by sanding the hardened jointcompound is preferably less than 20 mg/m3.

It is desirable that the dust-reduction additive serve to suppress theformation of airborne particles without significantly interfering withthe desired characteristics of the joint compound. The present inventionin fact discloses a joint compound that has a synergistic combination ofimproved dust generation property, improved water resistance, andimproved adhesive property.

The joint compound formulations include a conventional filler materialand a binder material, such as a resin. The joint compound can alsoinclude a surfactant, which may or may not serve to suppress airbornedust formation, and a thickening agent. Prior to hardening, the jointcompound preferably includes a sufficient amount of water to form amud-like spreadable material which can be applied to the wall surface.The present invention further provides an additive which can be admixedwith conventional joint compounds to reduce the quantity of dustgenerated during sanding. The dust-reduction additive can be used withboth drying type (i.e., ready mixed) or setting type joint compounds.

The present invention also provides a method of reducing the quantity ofairborne dust generated by sanding a fully hardened joint compound whichincludes mixing a sufficient quantity of a dust-reduction additive withthe joint compound prior to applying the joint compound to a wallsurface.

In some embodiments, the joint compound can comprise the dust-reductionadditive emulsion and can have a contact angle of about 90 to about 130degrees, a pH below 12, and a Cobb value of about 1.0 to about 1000grams per square meter.

In some embodiments, the joint compound can further comprise a rheologymodifier, a binder, a thickener, and a filler. In some embodiments, thejoint compound can further comprise calcium carbonate, or cristobalite,or a micro-roughened filler, or gypsum, or mica, or clay, or thickener,or a latex binder, or talc, or perlite, or expanded perlite, orcombinations thereof. In some embodiments, the joint compound cancomprise the low-dust wax emulsion which can comprise water, polyvinylalcohol, microcrystalline-wax, or montan wax, or synthetic wax, orcombinations thereof, a base, and a dispersant.

This invention also relates to a low-dust wax emulsion, the wax emulsioncomprising colloidally-protected, microcrystalline-wax-basedmicrostructure that has microcrystalline-wax chemically tethered to anemulsifier such as montan wax, a wax containing organic acids and/oresters, or an emulsifier containing a mixture of organic acids such asstearic acid and/or esters, or combinations thereof, the emulsifier, inturn, chemically tethered to a stabilizer polyvinyl alcohol, wherein thePVOH forms an encapsulation around the microcrystalline-wax.

In some embodiments, the joint compound shows a peak airborne dustproduction being reduced from about 10% to about 98% compared to thecommercially available joint compound dust reduction additive.

In some embodiments, the joint compound can have a pH below 9. In someembodiments, the joint compound can have a contact angle of about 60 toabout 130 degrees. In some embodiments, the joint compound can begenerally hydrophobic and can have a contact angle of about 110 to about130 degrees. In some embodiments, the joint compound can have a Cobbvalue of about 1.0 to about 1000 grams per square meter. In someembodiments, the joint compound can have a Cobb value of about 65 gramsper square meter.

In some embodiments, the joint compound can further comprise a rheologymodifier, a binder, a thickener, and a filler. In some embodiments, thejoint compound can further comprise calcium carbonate, or cristobalite,or a micro-roughened filler, or gypsum, or mica, or clay, or thickener,or a latex binder, or talc, or perlite, or expanded perlite, orcombinations thereof. In some embodiments, the joint compound cancomprise wax emulsion stabilized with polyvinyl alcohol. In someembodiments, the joint compound can comprise wax emulsion comprisingsynthetic wax. In some embodiments, the joint compound can comprise waxemulsion, the wax emulsion can comprise synthetic wax includingpolyethylene glycol or methoxypolyethylene glycol, or both polyethyleneglycol and methoxypolyethylene glycol.

In some embodiments, the joint compound can comprise wax emulsion andsilicones, or siloxanes, or siliconates, or fluorinated compounds, orstearates, or combinations thereof.

In some embodiments, the joint compound can comprise wax emulsion, thewax emulsion can be formed by mixing a combination of water, polyvinylalcohol, and microcrystalline-wax, or montan wax, or synthetic wax, orcombinations thereof.

In some embodiments, the joint compound can comprise the low-dust waxemulsion and silicones, or siliconates, or fluorinated compounds, orstearates, or combinations thereof. In some embodiments, the silicones,siliconates, fluorinated compounds, or stearates can be selected fromthe group consisting of metal siliconate salts, potassium siliconate,poly hydrogen methyl siloxane, polydimethyl siloxane, stearate-basedsalts, and combinations thereof.

In some embodiments, the joint compound can comprise the wax emulsionand optionally at least one thickener, preferably a cellulose etherbased thickener.

More specifically, this invention relates to a low-dust joint compoundcomposition comprising:

(i) a dust reduction additive emulsion comprising colloidally-protectedmicrocrystalline-wax-based (CMWB) microstructures; and

(ii) a first water.

In one embodiment, this invention further relates to the low-dust jointcompound composition as recited above, wherein said dust reductionadditive emulsion comprises said CMWB microstructure comprising:

(A) a wax core,

wherein said wax core comprises a microcrystalline-wax component and anon-microcrystalline-wax component,

-   -   wherein said microcrystalline-wax component comprises at least        one linear alkane wax defined by the general formula CnH2n+2,        where n ranges from 13-80,    -   wherein said non-microcrystalline-wax component comprises at        least one wax selected from the group consisting of animal-based        wax, plant-based wax, mineral wax, synthetic wax, a wax        containing organic acids and/or esters, anhydrides, an        emulsifier containing a mixture of organic acids and/or esters,        and combinations thereof; and

(B) a polymeric shell,

-   -   wherein said polymeric shell comprises at least one polymer        selected from polyvinyl alcohol, polyvinyl alcohol copolymers,        polyvinyl alcohol terpolymers, polyvinyl acetate, polyvinyl        acetate copolymers, polyvinyl acetate terpolymers, cellulose        ethers, polyethylene oxide, polyethyleneimines,        polyvinylpyrrolidone, polyvinylpyrrolidone copolymers,        polyethylene glycol, polyacrylamides and        poly(N-isopropylamides), pullulan, sodium alginate, gelatin,        starches, and combinations thereof.

In one embodiment, this invention also relates to the low-dust jointcom-pound composition as recited above, wherein said polymeric shellcomprises polyvinyl alcohol.

In yet another embodiment, this invention relates to the low-dust jointcompound composition as recited above, further comprising at least onecomponent from a filler; a binder; a thickener; a non-leveling agent; apreservative; a rheology modifier; and a surfactant.

In another embodiment, this invention relates to the low-dust jointcompound composition as recited above, wherein:

-   -   said filler is selected from calcium carbonate (CaCO₃), calcium        sulfate dihydrate (CaSO₄2H₂O), calcium sulfate hemihydrate        (CaSO₄-½H₂O), glass micro bubbles, mica, perlite, talc,        limestone, pyrophyllite, silica, diatomaceous earth, and        combinations thereof; said binder is selected from polyvinyl        acetate, polyvinyl alcohol, ethylene vinyl acetate co-polymer,        vinylacrylic copolymer, styrenebutadiene, polyacrylamide,        acrylic polymers, latex, natural starch, synthetic starch,        casein, and combinations thereof; said thickener is selected        from methyl cellulose, hydroxypropyl cellulose, hydroxypropyl        methyl cellulose, hydroxyethyl cellulose, hydroxyethyl methyl        cellulose, hydroxyethyl hydroxypropyl cellulose, ethyl        hydroxyethyl cellulose, sodium carboxymethyl cellulose, and        combinations thereof; and    -   said non-leveling agent is selected from attapulgite clay,        bentonite, illite, kaolin, sepiolite, clays mixed with starches,        and combinations thereof.

In yet another embodiment, this invention relates to the low-dust jointcompound composition as recited above, further comprising at least oneof cristobalite, a microroughened filler, clay, expanded perlite, andcombinations thereof.

In one embodiment, this invention relates to the low-dust joint compoundcomposition as recited above, wherein said dust-reduction additiveemulsion further comprises a second water; a base; and a dispersant.

In other embodiment, this invention relates to the low-dust jointcompound composition as recited above, wherein said dispersant isselected from a dispersant having sulfur; a dispersant having asulfur-containing group in the compound; sulfonic acid (R—S(═O)2-OH);sulfonic acid salts, wherein the R groups is functionalized withhydroxyl, or carboxyl; lignosulfonate; lignosulfonic acid; naphthalenesulfonic acid; sulfonate salt of lignosulfonic acid; sulfonate salt ofnaphthalene sulfonic acid; derivatized lignosulfonic acid; derivatizednaphthalene sulfonic acid; functionalized lignosulfonic acid;functionalized naphthalene sulfonic acid; magnesium sulfate;polycarboxylate; ammonium hepta molybdate; combination of ammonium heptamolybdate and starch; alkyl quaternary ammonium; montmorillonite clay;non-ionic surfactants; ionic surfactants; zwitterionic surfactants; andmixtures thereof.

In yet another embodiment, this invention relates to the low-dust jointcompound composition as recited above, wherein said base is selectedfrom monoethanol amine; diethanol amine; triethanol amine; imidazole;potassium siliconate; and combinations thereof.

In one embodiment, this invention relates to the low-dust joint compoundcomposition as recited above, wherein the weight of said dust reductionadditive emulsion is in the range of from about 0.1% to about 20% byweight of said low-dust joint compound composition.

In another embodiment, this invention relates to the low-dust jointcom-pound composition as recited above, wherein the weight of said dustreduction additive emulsion is in the range of from about 0.1% to about10% by weight of said low-dust joint compound composition.

In another embodiment, this invention relates to the low-dust jointcom-pound composition as recited above, wherein the peak air-borne dustgeneration of said low-dust joint compound is less than 100 mg/m3.

In yet another embodiment, this invention relates to the low-dust jointcompound composition as recited above, wherein the quantity of dustgenerated upon sanding of said low-dust joint compound composition isreduced at least by 5%.

In another embodiment, this invention relates to the low-dust jointcom-pound composition as recited above, wherein the quantity of dustgenerated upon sanding of said low-dust joint compound composition isreduced at least by 80%.

In one embodiment, this invention relates to the low-dust joint compoundcomposition as recited above, further comprising at least one componentfrom a silicone, a siliconate, a fluorinated compound, a stearate, or acombination thereof.

In yet another embodiment, this invention relates to the low-dust jointcompound composition as recited above, wherein the silicones,siliconates, fluorinated compounds, or stearates are selected from thegroup consisting of metal siliconate salts, potassium siliconate, polyhydrogen methyl siloxane, polydimethyl siloxane, stearate-based salts,and combinations thereof.

In one embodiment, this invention relates to a method of using saidlow-dust joint compound composition as recited above, said methodcomprising:

-   -   (I) applying said composition to a joint between adjacent        wallboard panels;    -   (II) allowing said composition to dry; and    -   (III) sanding said dried composition.

In another embodiment, this invention relates to a method of using saidlow-dust joint compound composition as recited above, said method forreducing the quantity of dust generated by a joint-compound composition,said method comprising the steps of:

-   -   (I) providing a joint-compound composition comprising a filler,        a first water, binder, and at least one of a defoamer, wetting        agent, preservative, fungicide, thickener, non-leveling agent,        surfactant, and a solvent; and    -   (II) subsequently adding a sufficient quantity of a        dust-reduction additive emulsion as described previously to said        joint-compound composition to reduce the quantity of dust        generated by sanding the hardened joint-compound composition by        at least 5%.

In one embodiment, this invention relates to a method for reducing thequantity of dust generated by a joint-compound as recited above, whereinthe quantity of dust generated by sanding said hardened drywalljoint-compound is reduced by at least 80%.

In yet another embodiment, this invention relates to a method forreducing the quantity of dust generated by a joint-compound as recitedabove, wherein said joint com-pound composition has a contact angle ofabout 60° to about 150°; and/or wherein said joint compound compositionhas a Cobb value of about 5.0 to about 100 g/m².

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosed aspects will hereinafter be described in conjunction withthe appended drawings, provided to illustrate and not to limit thedisclosed aspects, wherein like designations denote the elements.

FIG. 1 illustrates an example process of one embodiment of thedisclosure.

FIG. 2 describes the particle model of a unitary microcrystalline-waxparticle that has been stabilized in the colloidal dispersion.

FIG. 3 illustrates a wall having an example embodiment of the disclosedjoint compound applied thereon.

FIG. 4 shows the test enclosure used to sand test specimens and measurethe quantity of airborne dust particles generated.

FIG. 5 shows comparison of air-borne numbers for a commercial sample,paraffin wax emulsion based dust reduction additive, andmicrocrystalline-wax based dust reduction additive.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The terms “approximately”, “about”, and “substantially” as used hereinrepresent an amount close to the stated amount that still performs adesired function or achieves a desired result. For example, the terms“approximately”, “about”, and “substantially” may refer to an amountthat is within less than 10% of, within less than 5% of, within lessthan 1% of, within less than 0.1% of, and within less than 0.01% of thestated amount.

General Embodiments

Embodiments of the present disclosure provide a dust reduction additive(“DRA”) comprising colloidally-protected, microcrystalline-wax-based(“CMWB”) microstructures in an emulsion form. In another embodiment, thepresent invention relates to the process of preparing such dust reducingadditive emulsions. Dust reducing additive refers to any ingredientcapable of preventing, minimizing, suppressing, reducing, or inhibitingthe formation of particles capable of becoming airborne.

The expressions “airborne particles” or “airborne dust particles” referto fine particles generated during the sanding or abrading of thecompound which are capable of being carried by or through the air. Wallrepair compound refers generally to compositions useful for filling andrepairing cracks, holes, and other imperfections in surfaces such asdrywall, wood, plaster, and masonry.

Wall repair compounds include interior finishing and patch compoundssuch as joint compound, spackling compound, wood fillers, plasters,stucco, and the like. The joint compound can also include a thickener,and other materials found in conventional joint compounds. While thedisclosure infra describes the DRA of the present invention in thecontext of a joint compound, the DRA emulsion can also be used withother wall-repair compounds.

The present invention also relates to low-dust joint compoundscomprising the dust reducing additive and methods for preparing suchlow-dust joint compounds. By “low-dust joint compound” is meant a jointcompound comprising DRA emulsion in which the dust formation in form ofairborne particles is lower than the same joint compound not comprisingthe DRA emulsion. According to the present invention, there are providedjoint compound compositions suitable for filling and repairing cracks,holes, or other imperfections in a wall surface, such as the jointsbetween adjacent wallboard panels. The compositions of the presentinvention include a dust reducing additive combined with conventionalwall repair compound materials including a filler and a binder to form alow dust wall repair compound.

In addition to providing a low-dust property, the joint compoundcompositions of the present invention also provide adhesive propertiesto the joint compound to which it is added.

The joint compound may be used to create a low-dust barrier at walljoints, as well as at holes, such as nail holes, through a wall, therebyreducing the dust generated during processing of the joint compound andpreventing moisture from passing through the walls. The joint compoundmay be used, for example, in construction of houses or commercialbuildings.

In one embodiment, the joint compound comprises the dust reducingadditive that comprises an activated montan and polyvinylalcohol-stabilized microcrystalline-wax emulsion described furtherbelow. By doing so, the resulting dried joint compound surface canexhibit a low-dust environment and in some embodiments, even a highcontact angle. Further, the disclosed joint compound formed from a waxemulsion can avoid deleterious effects on key desirable performanceproperties of the joint compound such as adhesion.

In accordance with a characterizing feature of the present invention,the joint compound comprises the DRA emulsion which minimizes thequantity of airborne particles generated, for example, during sanding ofthe hardened joint compound. The additive generally comprises less than20% of the joint compound total wet weight. More preferably, the dustreducing additive comprises between about 0.1% and about 10% of thejoint compound by wet weight percent and, most preferably, between about0.5% and about 5% In one embodiment, the DRA is selected from any one ofthe following weight percentages:

0.1, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19,and 20.

The weight percentage of DRA emulsion in the joint compound can be anynumber within the range defined by any two numbers above, including theendpoints. The dust reducing additive of the present invention isdescribed in detail infra.

Many ingredients have been found to effectively reduce the quantity ofairborne particles generated when sanding the joint compound includingoils such as animal, vegetable, and mineral oils (saturated andunsaturated), and oils derived from petroleum, pitch, natural andsynthetic waxes, microcrystalline-wax, solvents which evaporate slowerthan water, terpenes, glycols, surfactants, and mixtures thereof.However, the CMWB microstructure based DRA emulsion of the presentinvention unlocks the synergistic effect of the three desired propertiesin the joint compound, namely: dust reducing property and adhesion.

While the manner by which each additive serves to suppress the formationof particles capable of becoming airborne is not fully understood, somegeneral observations have been made. It is possible that the dustreducing additive may cause the dust particles to agglomerate or sticktogether, thereby forming large heavy particles which tend not to becomeor remain airborne. The invention, however, is not intended to belimited to any particular mechanism.

Dust Reducing Additive

Definitions

For the purposes of this invention, a “colloidal dispersion” is adispersion of a discontinuous phase in a continuous phase, comprisingcolloidally-protected microcrystalline-wax-based microstructures.

By “wax” is meant any naturally occurring or synthetically occurringwax. It also includes blends or mixtures of one or more naturallyoccurring and/or synthetically occurring waxes. Those of animal origintypically consist of wax esters derived from a variety of carboxylicacids and fatty alcohols. The composition depends not only on species,but also on geographic location of the organism. Because they aremixtures, naturally produced waxes are softer and melt at lowertemperatures than the pure components. Waxes are further discussedinfra.

Microcrystalline-Wax

Generally, two chemically different waxy materials are extracted fromcrude oil: (1) paraffin wax or macro-wax; and (2) microcrystalline-wax.Microcrystalline-wax is a refined mixture of solid, saturated aliphatichydrocarbons. It is characterized by a higher molecular weight branchedmolecular structure, longer hydrocarbon chains, and higher naphthenichydrocarbon content, compared to the paraffin wax that contains mostlyunbranched alkanes.

The microcrystalline-wax crystal structure is much finer than paraffinwax, which directly impacts many of the physical properties. Typicalmicrocrystalline wax crystal structure is small and thin, making themmore flexible than paraffin wax. The fine crystal structure also enablesmicrocrystalline-wax to bind solvents or oil, and thus prevent thesweating-out of compositions. Also, the microcrystalline-wax contains ahigher amorphous content compared to the paraffin wax.

Microcrystalline waxes are produced by de-oiling heavy distillates suchas petrolatum during petroleum refining. This by-product is thende-oiled at a wax refinery. Depending on the end use and desiredspecification, the product then may have its odor removed and colorremoved.

Microcrystalline-waxes are tougher, more flexible and generally higherin melting point than paraffin wax. They are generally darker, moreviscous, denser, tackier and more elastic than paraffin waxes, and havea higher molecular weight and melting point. The elastic and adhesivecharacteristics of microcrystalline waxes are related to theirnon-straight chain components.

Microcrystalline waxes when produced by wax refiners are typicallyproduced to meet a number of ASTM specifications. These include congealpoint (ASTM D938), needle penetration (D1321), color (ASTM D6045), andviscosity (ASTM D445). Microcrystalline waxes can generally be put intotwo categories: “laminating” grades and “hardening” grades. Thelaminating grades typically have a melt point of 140-175 F (60-80 C) andneedle penetration of 25 or above. The hardening grades will range fromabout 175-200 F (80-93 C) and have a needle penetration of 25 or below.Color in both grades can range from brown to white, depending on thedegree of processing done at the refinery level.

Microcrystalline-wax is often used in making of tire and rubber,candles, adhesives, corrugated board, cosmetics, and castings.Microcrystalline-waxes are excellent materials to use when modifying thecrystalline properties of paraffin wax. The microcrystalline-wax hassignificantly more branching of the carbon chains that are the backboneof paraffin wax. This is useful when some desired functional changes inthe paraffin are needed, such as flexibility, higher melt point, andincreased opacity. They are also used as slip agents in printing ink.

TABLE 1 Comparison of Microcrystalline and Paraffin Waxes Paraffin-WaxMicrocrystalline-Wax Mainly unbranched alkanes Mainly branched alkanesCrystalline Amorphous Brittle Malleable Translucent Opaque Low meltingHigher melting (48 to 70° C.) (54 to 95° C.)

By “emulsion” or “microcrystalline-wax-based emulsion” is meant anaqueous colloidally occurring dispersion or mixture in a liquid orpaste-like form comprising wax materials, which has both thediscontinuous and the continuous phases, preferably as liquid. Forexample, an aqueous microcrystalline-wax system can either be a generalcolloid, or it can be an emulsion (which is a type of colloid),depending on the melt temperature of the emulsified microcrystalline-waxversus the use temperature. In the disclosure below, the term “emulsion”is used. It should be noted, however, that a colloidal dispersion isalso within the scope of the present invention.

By “colloidally-protected microcrystalline-wax-based microstructure”(CMWB microstructure) is meant a colloidal dispersion or emulsion,wherein the microstructure is colloidally protected with a wax or alower fraction hydrocarbon core. The microstructure can exist in adispersion or emulsion form.

Colloidally-Protected Microcrystalline-Wax-Based Microstructures

This invention relates to DRA materials that comprise CMWBmicrostructures, preferably in an emulsion form. They have beenalternatively called “CMWB microstructure based DRA emulsion,” or “DRAemulsion,” or “DRA emulsion comprising CMWB microstructure.” CMWBmicrostructures have a microcrystalline-wax core and film or casing ofpolymeric moieties which are adhered to the core via secondary forcessuch as hydrogen bonding or Van Der Waals forces as opposed to amechanical shell over a core in a classical core-shell structure. CMWBmicrostructures are described in detail below. In the aqueous emulsionof the DRA comprising the CMWB microstructures, the core may be fully orpartially encapsulated, in that the colloidal shell is not a physicalshell like that of a typical core-shell structure. The DRA emulsioncomprising CMWB microstructure provides low-dust property and adhesionproperty to the joint compound to which it is added.

CMWB Microstructure Shell

The polymers selected for the shell of the CMWB microstructures forlow-dust joint compound applications are one or more of the following:

Polyvinyl alcohol and copolymers, cellulose ethers, polyethylene oxide,polyethyleneimines, polyvinylpyrrolidone, and copolymers, polyethyleneglycol, polyacrylamides and poly(Nisopropylamides, pullulan, sodiumalginate, gelatin, and starches. Polyvinyl alcohol and copolymers arepreferred.CMWB Microstructure Core

The core of the colloidally-protected microcrystalline-wax-basedmicrostructures can be a microcrystalline-wax as defined previously.This invention also envisions a blend of microcrystalline-wax andparaffin-wax, wherein the microcrystalline-wax is at least 50% by weightof the combined content of the microcrystalline-wax and theparaffin-wax. The content of microcrystalline-wax in such a blend can beany one of the following numbers or an inclusive range defined by anytwo numbers expressed in percentage:

30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, and 100.

Preferably the core comprises the microcrystalline-wax in a substantialamount, for example, greater than 90%.

The melting point of core waxes lower than the melting point of thecolloidally-protective polymeric shell.

Some embodiments of the present invention envision microcrystalline-waxthat comprises branched structures as well as a blend or mixture oflinear and branched structures of the microcrystalline-wax. Thisinvention also embodies mixtures or blends of waxes with two or morecarbon numbers that may either be linear, branched, or blends of linearand branched structures. For example, a wax could be a mixture of C₁₅linear and C₂₀ linear hydrocarbon alkane wax. In another example, thewax could be a mixture of C16 linear and C16 branched hydrocarbon alkanewax. In yet another example, the wax could be a mixture of C15 linear,C16 linear, and C20 branched. In yet another example, the wax could be amixture of C18 linear, C18 branched.

Waxes usable as core in the CMWB microstructure-based DRA emulsion ofthe present invention are described.

Waxes

For the purposes of the present invention, waxes include naturallyoccurring waxes and synthetic waxes. Naturally occurring waxes includeplant based waxes, animal waxes, and mineral waxes. Synthetic waxes aremade by physical or chemical processes.

Examples of plant based waxes include mixtures of unesterifiedhydrocarbons, which may predominate over esters. The epicuticular waxesof plants are mixtures of substituted long-chain aliphatic hydrocarbons,containing alkanes, alkyl esters, sterol esters, fatty acids, primaryand secondary alcohols, diols, ketones, aldehydes, aliphatic aldehydes,primary and secondary alcohols, β-diketones, triacylglycerols, and manymore. The nature of the other lipid constituents can vary greatly withthe source of the waxy material, but they include hydrocarbons. Specificexamples of plant wax include Carnauba wax, which is a hard wax obtainedfrom the Brazilian palm Copernicia prunifera, which contains the estermyricyl cerotate. Other plant based waxes include candelilla wax,ouricury wax, jojoba plant wax, bayberry wax, Japan wax, sunflower wax,tall oil, tallow wax, rice wax, and tallows.

Animal wax includes beeswax as well as waxes secreted by other insects.A major component of the beeswax used in constructing honeycombs is theester myricyl palmitate which is an ester of triacontanol and palmiticacid. Spermaceti occurs in large amounts in the head oil of the spermwhale. One of its main constituents is cetyl palmitate, another ester ofa fatty acid and a fatty alcohol. Lanolin is a wax obtained from wool,consisting of esters of sterols. Other animal wax examples includelanocerin, shellac, and ozokerite.

Examples of mineral waxes include montan wax, microcrystalline wax andparaffin wax. Although many natural waxes contain esters, paraffin waxesare hydrocarbons, mixtures of alkanes usually in a homologous series ofchain lengths. Montan wax is a fossilized wax extracted from coal andlignite. It is very hard, reflecting the high concentration of saturatedfatty acids/esters and alcohols. Montan wax includes chemical componentsformed of long chain alkyl acids and alkyl esters having chain lengthsof about 24 to 30 carbons. In addition, natural montan includes resinacids, polyterpenes and some alcohol, ketone and other hydrocarbons suchthat it is not a “pure” wax. The saponification number of montan, whichis a saponifiable wax, is about 92 and its melting point is about 80° C.Waxes comprising esters and/or acids may act as emulsifiers to theparaffins.

Synthetic waxes include waxes based on polypropylene, polyethylene, andpolytetrafluoroethylene. Other synthetic waxes are based on fatty acidamines, Fischer-Tropsch, and polyamides, polyethylene and relatedderivatives. Some waxes are obtained by cracking polyethylene at 400° C.The products have the formula (CH₂)_(n)H₂, where n ranges between about50 and 100.

Also, outside of the building products context, in addition to waxesthat occur in natural form, there are various known synthetic waxeswhich include synthetic polyethylene wax of low molecular weight, i.e.,molecular weights of less than about 10,000, and polyethylenes that havewax-like properties. Such waxes can be formed by direct polymerizationof ethylene under conditions suitable to control molecular weight.Polyethylenes with molecular weights in about the 2,000-4,000 range arewaxes, and when in the range of about 4,000-12,000 become wax resins.

Fischer-Tropsch waxes are polymethylene waxes produced by a particularpolymerization synthesis, specifically, a Fischer-Tropsch synthesis(polymerization of carbon monoxide under high pressure, high temperatureand special catalysts to produce hydrocarbon, followed by distillationto separate the products into liquid fuels and waxes). Such waxes(hydrocarbon waxes of microcrystalline, polyethylene and polymethylenetypes) can be chemically modified by, e.g., air oxidation (to give anacid number of 30 or less and a saponification number no lower than 25)or modified with maleic anhydride or carboxylic acid. Such modifiedwaxes are more easily emulsified in water and can be saponified oresterified. Other known synthetic waxes are polymerized alpha-olefins.These are waxes formed of higher alpha-olefins of 20 or more carbonatoms that have wax like properties. The materials are very branchedwith broad molecular weight distributions and melting points rangingabout 54° C. to 75° C. with molecular weights of about 2,600 to 2,800.Thus, waxes differ depending on the nature of the base material as wellas the polymerization or synthesis process, and resulting chemicalstructure, including the use and type of any chemical modification.

In one embodiment of the invention, the wax used for the preparation ofthe dispersion or emulsion is used in a micronized, pulverized form.U.S. Pat. Nos. 8,669,401 and 4,846,887 show exemplary micronizationprocesses. Both these patents are incorporated by reference herein as iffully set forth.

In one embodiment, the emulsifiers for this invention include montanwax, esters/acids, styrene-maleic anhydride, polyolefin maleicanhydride, or other anhydrides, carnauba wax, rice wax, sunflower wax.

Theory for Colloidally-Protected Microcrystalline-Wax-BasedMicrostructures

Generally speaking, two scientific theories have been proposed toexplain the stability of CMWB microstructures that comprise the DRAemulsion materials of the present invention, namely, steric hindranceand electrostatic repulsion. Applicants do not wish to be bound by thesetheories, however. Applicants believe their invention relates tomicrocrystalline-wax-based dispersions that may or may not relate to thetwo theories. It is possible that one or both theories or neither of thetwo may explain the CMWB microstructures of the present invention.

As described in FIG. 1, in the first step, a colloidally-protectedmicrocrystalline-wax based microstructure in an emulsion is prepared.The emulsion is prepared according to the specification for their use invariety of applications. For a general understanding of the method ofmaking the exemplary wax emulsion, reference is made to the flow diagramin FIG. 1. As shown in 101, first the microcrystalline-wax componentsmay be mixed in an appropriate mixer device. Then, as shown in 102, thewax component mixture may be pumped to a colloid mill or homogenizer. Asdemonstrated in 103, in a separate step, water, and any emulsifiers,stabilizers, or additives (e.g., ethylene-vinyl alcohol-vinyl acetateterpolymer) are mixed. Then the aqueous solution is pumped into acolloid mill or homogenizer in 104. Steps 101 and 103 may be performedsimultaneously, or they may be performed at different times. Steps 102and 104 may be performed at the same time, so as to ensure properformation of droplets in the emulsion. In some embodiments, steps 101and 102 may be performed before step 103 is started. Finally, as shownin 105, the two mixtures from 102 and 104 are milled or homogenized toform an aqueous wax-based emulsion.

FIG. 2 describes the particle model of a unitary microcrystalline-waxparticle that has been stabilized in the colloidal dispersion.Applicants do not wish to be bound by the theory of the unitarymicrocrystalline-wax particle stabilized in the dispersion. According tothis model, the hydrophobic hydrocarbon “tail” of the montan is embeddedin the microcrystalline-wax particle. The “head” of montan, which ishydrophilic is then tethered to polyvinyl alcohol. The first mechanismby which many of the wax emulsions (colloidal dispersions) arestabilized is the steric hindrance mechanism. According to thismechanism, high molecular weight polymers (e.g. PVOH) are tethered tothe outer surface of a microcrystalline-wax particle and surround it.Due to steric hindrance, the PVOH molecules surrounding each waxparticle then prevent adjacent microcrystalline-wax particles fromcoalescing.

Alternatively, electrostatic repulsion helps with the stabilization ofthe colloidal dispersions. In this mechanism, the montan wax particle,which contains acid or ester groups (either inherently or mixed in), isfirst saponified with a base, converting the acid or ester groups tonegatively charged carboxylate moieties. Because of their polar nature,these negatively charged carboxylate moieties exist at the water/waxinterface, giving the surrounded microcrystalline wax particle a netnegative charge. These negative charges on adjacent wax particles thenconstitute a repulsive force between particles that effectivelystabilizes the dispersion (emulsion).

Thus, according to one model, as shown in FIG. 2, a microcrystalline-waxparticle is enclosed in a “web” of PVOH polymeric chains. This is notakin to a shell of a typical core-shell particle, but the PVOH looselyprotects (colloidally protects) the microcrystalline-wax particle. Onecould envision the microcrystalline-wax particle as a solid ball or anucleus surrounded by polymeric chains like strings.

In another embodiment, and as shown in FIGS. 3 and 4, the polymer, forexample PVOH, forms a shell like physical film or casing such as a film(PVOH is an excellent film former), the casing herein is based onsecondary forces of attraction, e.g., Van der Waals forces. Hydrogenbonding may also be one of the forces for the encapsulation of the PVOHof the wax particles. Applicants do not wish to be bound by this theory.However, the model does explain the wax particle with the PVOH casingover it. In the above examples, PVOH is used as an exemplary polymericsystem. However, other polymeric systems used herein, or theircombinations can also be used to prepare the colloidally-protectedmicrocrystalline-wax-based microstructures.

Dust Reduction Additive Emulsion

Exemplary emulsion comprising CMWB microstructure for use in, forexample, as a dust reduction additive (and for water-resistance) in ajoint compound are now described in greater detail, as follows.

In one embodiment, the microcrystalline-wax emulsion may comprise water,a base, one or more waxes optionally selected from the group consistingof slack wax, montan wax, and microcrystalline-wax, and a polymericstabilizer, such as ethylene-vinyl alcohol-vinyl acetate terpolymer orpolyvinyl alcohol. Further, carnauba wax, sunflower wax, tall oil,tallow wax, rice wax, and any other natural or synthetic wax oremulsifier containing organic acids and/or esters can be used to formthe wax emulsion.

Water may be provided to the emulsion, for example in amounts of about30% to about 60% by weight of the emulsion. The solids content of thewax emulsion is preferably about 40% to about 70% by weight of theemulsion. Other amounts may be used.

In some embodiments, a dispersant and/or a surfactant may be employed inthe wax emulsions. Optional dispersants, include, but are not limited tothose having a sulfur or a sulfur-containing group(s) in the compoundsuch as sulfonic acids (R—S(═O)2-OH) and their salts, wherein the Rgroups may be otherwise functionalized with hydroxyl, carboxyl or otheruseful bonding groups. In some embodiments, higher molecular weightsulfonic acid compounds such as lignosulfonate, lignosulfonic acid,naphthalene sulfonic acid, the sulfonate salts of these acids, andderivatized or functionalized versions of these materials are used inaddition or instead. An example lignosulfonic acid salt is Polyfon® Havailable from MeadWestvaco Corporation, Charleston, S.C. Otherdispersants may be used, such as magnesium sulfate, polycarboxylatetechnology, ammonium hepta molybdate/starch combinations, non-ionicsurfactants, ionic surfactants, zwitterionic surfactants and mixturesthereof, alkyl quaternary ammonium montmorillonite clay, etc. Similarmaterials may also be used, where such materials may be compatible withand perform well with the formulation components.

In one embodiment, a dispersant and/or surfactant may comprise about0.01% to about 5.0% by weight of the wax emulsion formulationcomposition, preferably about 0.1% to about 2.0% by weight of the waxemulsion formulation composition. Other concentrations may be used.

The wax component of the emulsion may include at least one wax which maybe slack wax, or a combination of montan wax and slack wax. The totalwax content may be about 30% to about 60%, more preferably about 30% toabout 40% by weight of the emulsion. Slack wax may be any suitable slackwax known or to be developed which incorporates a material that is ahigher petroleum refining fraction of generally up to about 20% byweight oil. In addition to, or as an alternative to slack wax,microcrystalline-waxes of a more refined fraction are also useful withinthe scope of the invention.

Suitable microcrystalline-waxes may be any suitable wax, and preferablywaxes with melting points of from about 40° C. to about 110° C.,although lower or higher melting points may be used if drying conditionsare altered accordingly using any techniques known or yet to bedeveloped in the composite board manufacturing arts or otherwise. Thus,microcrystalline-waxes or less refined slack wax may be used.Optionally, synthetic waxes such as ethylenic polymers or hydrocarbontypes derived via Fischer-Tropsch synthesis may be included in addition.The wax emulsion used in the joint compound can be formed from slackwax, montan wax, microcrystalline-wax, carnauba wax, tall oil, sunflowerwax, rice wax, and any other natural or synthetic wax containing organicacids and/or esters, or combinations thereof. For example, synthetic waxused in the joint compound may comprise ethylenic polymers orhydrocarbon types, optionally derived via Fischer-Tropsch synthesis, orcombinations thereof. Optionally, the synthetic waxes can be added inconcentrations ranging from about 0.1% to about 8% of the dry weight ofthe joint compound or from about 0.5% to about 4.0% of the dry weight ofthe joint compound. In some embodiments, the wax emulsion is stabilizedby polyvinyl alcohol.

Montan wax, which is also known in the art as lignite wax, is a hard,naturally occurring wax that is typically dark to amber in color(although lighter, more refined montan waxes are also commerciallyavailable). Montan is insoluble in water, but is soluble in solventssuch as carbon tetrachloride, benzene and chloroform. In addition tonaturally derived montan wax, alkyl acids and/or alkyl esters which arederived from high molecular weight fatty acids of synthetic or naturalsources with chain lengths preferably of over 18 carbons, morepreferably from 26 to 46 carbons that function in a manner similar tonaturally derived montan wax are also within the scope of the inventionand are included within the scope of “montan wax” as that term is usedherein unless the context indicates otherwise (e.g., “naturallyoccurring montan wax”). Such alkyl acids are generally described asbeing of formula R—COOH, where R is an alkyl nonpolar group which islipophilic and can be from 18 to more than 200 carbons. An example ofsuch a material is octacosanoic acid and its corresponding ester whichis, for example, a di-ester of that acid with ethylene glycol. The COOHgroup forms hydrophilic polar salts in the presence of alkali metalssuch as sodium or potassium in the emulsion. While the alkyl portion ofthe molecule gets embedded within the microcrystalline-wax, the acidportion is at the microcrystalline-wax/aqueous medium interface,providing stability to the emulsion.

In some embodiments, the at least one wax component is made up of acombination of microcrystalline-wax and montan wax or of slack wax andmontan wax. Although it should be understood that varying combinationsof such waxes can be used. When using montan wax in combination with oneor more of the other suitable wax components, it is preferred thatmontan be present in an amount of about 0.1% to about 10%, morepreferably about 1% to about 4% by weight of the wax emulsion with theremaining wax or waxes present in amounts of from about 30% to about50%, more preferably about 30% to about 35% by weight of the waxemulsion.

In some embodiments, the wax emulsion includes polyvinyl alcohol (PVOH)of any suitable grade which is at least partially hydrolyzed. Thepreferred polyvinyl alcohol is at least 50%, and more preferably atleast 90%, and most preferably about 97-100% hydrolyzed polyvinylacetate. The PVA can be hydrolyzed to the extent defined by thepercentage numbers below:

50, 55, 60, 65, 70, 75, 80, 85, 90, 95, and 100.

The PVA can also be hydrolyzed up to the extent of a number that residesin the range defined by any two numbers above, including the endpoints.

Suitably, the polyvinyl alcohol is soluble in water at elevatedtemperatures of about 60° C. to about 95° C., but insoluble in coldwater. The hydrolyzed polyvinyl alcohol is preferably included in theemulsion in an amount of up to about 5% by weight, preferably 0.1% toabout 5% by weight of the emulsion, and most preferably about 2% toabout 3% by weight of the wax emulsion.

In some embodiments, the stabilizer comprises a polymer that is capableof hydrogen bonding to the carboxylate or similar moieties at thewater/microcrystalline-wax interface. Polymers that fit thehydrogen-bonding requirement would have such groups as hydroxyl, amine,and/or thiol, amongst others, along the polymer chain. Reducing thepolymer's affinity for water (and thus, its water solubility) could beachieved by inserting hydrophobic groups such as alkyl, alkoxy silanes,or alkyl halide groups into the polymer chain. The result may be apolymer such as ethylene-vinyl acetate-vinyl alcohol terpolymer (wherethe vinyl acetate has been substantially hydrolyzed). The vinyl acetatecontent may be between 0% to 15%. In some embodiments, the vinyl acetatecontent is between 0% and 3% of the terpolymer chain. The ethylene-vinylalcohol-vinyl acetate terpolymer may be included in the emulsion in anamount of up to about 10.0% by weight, preferably 0.1% to about 5.0% byweight of the emulsion. In some embodiments, ethylene-vinylalcohol-vinyl acetate terpolymer may be included in the emulsion in anamount of about 2% to about 3% by weight of the wax emulsion. An exampleethylenevinyl alcohol-vinyl acetate terpolymer that is available is theExceval AQ4104™, available from Kuraray Chemical Company.

The dust reduction additive wax emulsion may include a stabilizermaterial (e.g., PVOH, ethylene-vinyl alcohol-vinyl acetate terpolymer asdescribed above). The stabilizer may be soluble in water at elevatedtemperatures similar to those disclosed with reference to PVOH (e.g.,about 60° C. up to about 95° C.), but insoluble in cold water. Theactive species in the wax component (e.g., montan wax) may be thecarboxylic acids and esters, which may comprise as much as 90% of thewax. These chemical groups may be converted into carboxylate moietiesupon hydrolysis in a high pH environment (e.g., in an environmentincluding aqueous KOH). The carboxylate moieties may act as ahydrophilic portion or “head” of the molecule. The hydrophilic portionscan directly interface with the surrounding aqueous environment, whilethe rest of the molecule, which may be a lipophilic portion or “tail”,may be embedded in the hydrocarbon wax.

A stabilizer capable of hydrogen bonding to carboxylate moieties (e.g.,PVOH or ethylene-vinyl alcohol-vinyl acetate terpolymer as describedabove) may be used in the wax emulsion. The polar nature of thecarboxylate moiety may offer an optimal anchoring point for a stabilizerchain through hydrogen bonding. When stabilizer chains are firmlyanchored to the carboxylate moieties as described above, the stabilizermay provide emulsion stabilization through steric hindrance. Inembodiments where the wax emulsion is subsequently dispersed in awallboard (e.g., gypsum board) system, all the water may be evaporatedaway during wallboard manufacture. The stabilizer may then function as agate-keeper for repelling moisture. Decreasing the solubility of thestabilizer in water may improve the moisture resistance of the waxemulsion and the wallboard. For example, fully hydrolyzed PVOH may onlydissolve in heated, and not cool, water. For another example,ethylene-vinyl alcohol-vinyl acetate terpolymer may be even less watersoluble than PVOH. The ethylene repeating units may reduce the overallwater solubility. Other stabilizer materials are also possible. Forexample, polymers with hydrogen bonding capability such as thosecontaining specific functional groups, such as alcohols, amines, andthiols, may also be used. For another example, vinyl alcohol-vinylacetate-silyl ether terpolymer can be used. An example vinylalcohol-vinyl acetate-silyl ether terpolymer is Exceval R2015, availablefrom Kuraray Chemical Company. In some embodiments, combinations ofstabilizers are used.

In some embodiments, the wax emulsion comprises a base. For example, thewax emulsion may comprise an alkali metal hydroxide, such as potassiumhydroxide or other suitable metallic hydroxide, such as aluminum,barium, calcium, lithium, magnesium, sodium and/or zinc hydroxide. Thesematerials may serve as saponifying agents. Non-metallic bases such asderivatives of ammonia as well as amines (e.g., diethanolamine ortriethanolamine) can also be used. Combinations of the above-mentionedmaterials are also possible. If included in the wax emulsion, potassiumhydroxide is preferably present in an amount of 0% to 1%, morepreferably about 0.1% to about 0.5% by weight of the wax emulsion.

In some embodiments, an exemplary wax emulsion comprises: about 30% toabout 60% by weight of water; about 0.1% to about 5% by weight of alignosulfonic acid or a salt thereof; about 0% to about 1% by weight ofpotassium hydroxide; about 30% to about 50% by weight of wax selectedfrom the group consisting of microcrystalline-wax, slack wax andcombinations thereof; and about 0.1% to about 10% montan wax, and about0.1 to 5% by weight of ethylene-vinyl alcohol-vinyl acetate terpolymer.

The wax emulsion may further include other additives, including withoutlimitation additional emulsifiers and stabilizers typically used in waxemulsions, flame retardants, lig-nocellulosic preserving agents,fungicides, insecticides, biocides, waxes???, sizing agents, fillers,binders, additional adhesives and/or catalysts. Such additives arepreferably present in minor amounts and are provided in amounts whichwill not materially affect the resulting composite board properties.Preferably no more than 30% by weight, more preferably no more than 10%,and most preferably no more than 5% by weight of such additives arepresent in the wax emulsion.

Shown in the below tables are exemplary embodiments of a wax emulsion,although other quantities in weight percent may be used.

TABLE 2 First Exemplary Embodiment of Dust Reduction Additive EmulsionRaw Material Quantity in Weight Percent Water 58 Polyvinyl alcohol 2.70Dispersant (Optional) 1.50 Microcrystalline Wax 34.30 Montan Wax 3.50Biocide 0.02

TABLE 3 Second Exemplary Embodiment of Dust Reduction Additive EmulsionRaw Material Quantity in Weight Percent Water 58.80 Polyvinyl alcohol2.80 Diethanol Amine 0.04 Microcrystalline Wax 34.80 Montan Wax 3.50Biocide 0.10

The microcrystalline-wax emulsion may be prepared using any acceptabletechniques known in the art or to be developed for formulating waxemulsions, for example, the wax(es) are preferably heated to a moltenstate and blended together (if blending is required). A hot aqueoussolution is prepared which includes any additives such as emulsifiers,stabilizers, etc., ethylene-vinyl alcohol-vinyl acetate terpolymer (ifpresent), potassium hydroxide (if present) and lignosulfonic acid or anysalt thereof. The emulsifiers may also optionally be mixed with the waxblend. The wax is then metered together with the aqueous solution inappropriate proportions through a colloid mill or similar apparatus toform a wax emulsion, which may then be cooled to ambient conditions ifdesired.

In some embodiments, the wax emulsion may be incorporated with or coatedon various surfaces and substrates. For example, the wax emulsion may bemixed with gypsum to form a gypsum wallboard having improved moistureresistance properties.

Some or all steps of the above method may be performed in open vessels.However, the homogenizer may use pressure in its application.

Advantageously in some embodiments, the emulsion, once formed, is cooledquickly. By cooling the emulsion quickly, agglomeration and coalescenceof the wax particles may be avoided.

In some embodiments the wax mixture and the aqueous solution arecombined in a pre-mix tank before they are pumped into the colloid millor homogenizer. In other embodiments, the wax mixture and the aqueoussolution may be combined for the first time in the colloid mill orhomogenizer. When the wax mixture and the aqueous solution are combinedin the colloid mill or homogenizer without first being combined in apre-mix tank, the two mixtures may advantageously be combined underequivalent or nearly equivalent pressure or flow rate to ensuresufficient mixing.

In some embodiments, once melted, the wax emulsion is quickly combinedwith the aqueous solution. While not wishing to be bound by any theory,this expedited combination may beneficially prevent oxidation of the waxmixture.

In some embodiments, once melted, the wax emulsion is quickly combinedwith the aqueous solution. While not wishing to be bound by any theory,this expedited combination may beneficially prevent oxidation of the waxmixture.

Low-Dust Joint Compound

Embodiments of the disclosed CMWB microstructure based dust reducingadditive emulsion can be used to form a low-dust joint compound. Thejoint compound can be used to cover, smooth, or finish gaps in boards,such as joints between adjacent boards, screw holes, and nail holes. Thejoint compound can also be used for repairing surface defects on wallsand applying texture to walls and ceilings amongst numerous otherapplications. The joint compound comprises a filler material. Anyconventional filler material can be used in the present invention.Suitable fillers include calcium carbonate (CaCO₃) and calcium sulfatedihydrate (CaSO₄2H₂O commonly referred to as gypsum) for ready mixedtype joint compounds, and calcium sulfate hemihydrate (CaSO₄-½ H₂O) forsetting type joint compounds. The joint compound can also include one ormore secondary fillers such as glass micro bubbles, mica, perlite, talc,limestone, pyrophyllite, silica, and diatomaceous earth. The fillergenerally comprises from about 25% to about 95% of the weight of thejoint compound based on the total wet weight of the formulation (i.e.including water). More preferably, the filler comprises from about 55%to about 75% of the total wet weight, and most preferably, from about60% to about 70%.

Another ingredient usually present in joint compounds is a binder orresin. Suitable binders include polyvinyl acetate, polyvinyl alcohol,ethylene vinyl acetate co-polymer, vinylacrylic co-polymer,styrenebutadiene, polyacrylamide, other acrylic polymers, other latexemulsions, natural and synthetic starch, and casein. These binders canbe used alone or in combination with one another. The amount of bindercan range from about 1% to about 45% of the joint compound total wetweight. More preferably, the binder comprises from about 1% to about 20%of the total wet weight, and most preferably, from about 4% to about14%.

A surfactant can also be included in the joint compound formulation. Thesurfactant generally comprises less than about 3.5% of the jointcompound total wet weight, and preferably less than about 0.25%.

Many joint compound formulations also contain a cellulosic thickener,usually a cellulosic ether. Suitable thickeners include methylcellulose, hydroxypropyl cellulose, hydroxypropyl methyl cellulose,hydroxyethyl cellulose, hydroxyethyl methyl cellulose, hydroxyethylhydroxypropyl cellulose, ethyl hydroxyethyl cellulose, and sodiumcarboxymethyl cellulose (CMC). These thickeners can be used alone or incombination with one another. The amount of cellulosic thickener canrange from about 0.1% to about 2% by weight of the joint compound. Apreferred thickener is hydroxypropyl methyl cellulose available from DowChemical Company under the trade designation Methocel®.

Another ingredient that can be included in the joint compound of theinvention is a non-leveling agent. Suitable non-leveling agents includeclays such as attapulgus clay, bentonite, illite, kaolin and sepiolite,and clays mixed with starches. Thickeners, such as those describedabove, can also function as non-leveling agents.

To provide a lighter weight joint compound, glass bubbles or a speciallytreated expanded perlite can be added as described in U.S. Pat. No.4,454,267. Additional ingredients which can be utilized in the jointcompound are preservatives, fungicides, anti-freeze wetting agents,defoamers, flocculants, such as polyacrylamide resin, and plasticizers,such as dipropylene glycol dibenzoate.

The wax emulsion used in the joint compound can be formed from slackwax, montan wax, microcrystalline wax, carnauba wax, tall oil, sunflowerwax, rice wax, and any other natural or synthetic wax containing organicacids and/or esters, or combinations thereof. For example, synthetic waxused in the joint compound may comprise ethylenic polymers orhydrocarbon types, optionally derived via Fischer-Tropsch synthesis, orcombinations thereof. By way of further example, synthetic wax used inthe joint compound may comprise polyethylene glycol, methoxypolyethyleneglycol, or combinations thereof. Optionally, the synthetic waxes can beadded in concentrations ranging from about 0.1% to about 8% of the dryweight of the joint compound or from about 0.5% to about 4.0% of the dryweight of the joint compound. In some embodiments, the wax emulsion isstabilized by polyvinyl alcohol.

In some embodiments, perlite can be used in a joint compound to, forexample, control the density, shrinkage, and crack resistance of thejoint compound. In some embodiments, perlite need not be used (e.g.,where weight is not as much of a factor).

In some embodiments, mica can be used in a compound as well. Mica, whichis a low bulk density mineral, may be used as a filler or extender, andmay also improve crack resistance of the joint compound.

In some embodiments of the joint compound gypsum (calcium sulfatedihydrate) can also be used. Gypsum can be used to replace calciumcarbonate, or can be used in conjunction with calcium carbonate. In someembodiments, talc can be included in a joint compound to, for example,enhance application properties and can also be used as a white extenderpigment.

In some embodiments, clay can be used in a joint compound as, forexample, a non-leveling agent and/or a thickening agent that can controlthe viscosity or rheology of the final product. Clay can also helpenhance or create the water-holding properties of the joint compound.

In some embodiments, thickeners can be used to control the viscosity,affect the rheology, and affect the water holding characteristics of ajoint compound. For example, cellulose ether can be used as a thickener.

In some embodiments, binders can be used in a joint compound to, forexample, improve bonding to the substrate such as wallboard.

In some embodiments, a glycol can be used in a joint compound to providefunctional properties to the joint compound such as wet edge, open time,controlling drying time, and freeze/thaw stability.

In some embodiments, other rheology modifiers can also be used inconjunction with, or instead of, some of the above describedcompositions.

In some embodiments, fillers can be used in the joint compound. Forexample, calcium carbonate, calcium sulfate hemihydrate, or calciumsulfate dehydrate can all be used as fillers, though other materials canbe used as well. Further, thickeners, preservatives, binders, and otheradditives can be incorporated into the joint compound.

Other additives can also be added to the described joint compound inaddition to the wax emulsion. In some embodiments, metal siliconatesalts such as, for example, potassium siliconate, as well as siliconebased compounds such as, for example, poly hydrogen methyl siloxane andpolydimethyl siloxane, could provide advantageous water resistance to ajoint compound. In some embodiments, fluorinated compounds andstearate-based salts could also be used to provide advantageous waterresistance.

Wax emulsions can be particularly advantageous for use in a jointcompound as compared to, for example, non-emulsified and/ornon-stabilized waxes such as melted PEG M750. These non-emulsified waxescan impart severe deleterious effects on the adhesion properties of ajoint compound. Therefore, if the non-emulsified wax is to be used atall, it must be added in very low levels. On the other hand, waxemulsions, such as those described herein, can advantageously increasethe adhesion properties of a joint compound, at least due to theadhesive effects of the stabilizer, and thus can be added at higherdosage levels. The wax emulsions can then be useful as they can provideboth low dust properties as well as water repellency to the jointcompound. The wax emulsion can soften or melt when friction is applied,such as during cutting or sanding. Accordingly, dust can be agglomeratedby the softened wax emulsion, where it can be securely held.

Embodiments of the joint compound can be applied in thin layers to asurface. The joint compound can be applied by, for example, using atrowel or other straight edged tool. However, the application andthickness of the layers of joint compounds is not limiting. Further,multiple layers may be applied in order to obtain a smooth, attractivefinished wall. The number or layers applied is not limiting. In someembodiments, each layer can be allowed to dry prior to application ofthe next layer. In some embodiments, a second layer can be applied whenthe first layer is only partially dried. In some embodiments, the jointcompound can be spread over mesh or tape used to connect wallboards.

In some embodiments, the joint compound may also be used to patch andtexture interior walls. In some embodiments, the joint compound can bemade of water, preservative, calcium carbonate, mica, clay, thickener,binder (e.g., latex binder), and a wax emulsion. In addition to a latexbinder, other water soluble binders, such as polyvinyl alcohol, can beused as well. Other materials, such as talc, binders, fillers,thickening agents, preservatives, limestone, perlite, urea, defoamingagents, gypsum latex, glycol, and humectants can be incorporated intothe joint compound as well or can substitute for certain ingredients(e.g., talc can be used in place of, or in addition to mica; gypsum canbe used in place of, or in addition to calcium carbonate, etc.). In someembodiments, the calcium carbonate can be replaced either wholly orpartially with a surface micro-roughened filler that can further enhancethe joint compound's hydrophobicity. In some embodiments, Calcimatt™,manufactured by Omya AG, can be used. In some embodiments, cristobalite(silicon dioxide) such as Sibelite® M3000, manufactured by Quarzwerke,can be used. These fillers can be used alone or in combination. In someembodiments, the joint compound can be mixed in water. This mixture canthen be applied to a surface, e.g., hole or joint, and can be allowed todry. Once the water evaporates from the mixture, a dry, relatively hardcementitious material can remain. In some embodiments, shrinkage mayoccur upon drying.

FIG. 3 shows an example of a wall system incorporating an embodiment ofa low-dust joint compound. As shown, the wall system can be made of aplurality of boards 202. There is no limit to the amount of boards orthe positioning of boards next to one another. Where two boards 202 areadjacent to one another, a gap, or joint, can be formed. While theboards 202 themselves may be water-resistant, the joints may allow formoisture to pass through. Therefore, embodiments of the low-dust andwater-resistant joint compound 204 can be spread across the joints. Thecompound 204 can be spread on the joint to completely cover the joint.In some embodiments, the boards 202 can also contain holes. These holescan be formed by nailing the boards 202 into studs, or other attachmentmeans. Regardless of the reason for the hole, the compound 206 can alsobe used to cover the holes. The compound 206 can insert partial throughthe holes, or can cover the top of the holes, or both. The compound 206can cover any fastener, e.g. a screw or nail that is located in thehole. In some embodiments, compound 206 and 204 are the same compound.The application and thickness of the compound 204/206 on the boards 202is not limiting, and common methods of application can be used.

An example formula range of an embodiment of a low-dust water-resistantjoint compound using the above disclosed wax is shown in the below Table4:

TABLE 4 Exemplary Composition of a Low-Dust Joint Compound ComponentRange Water  20-55% Preservatives 0.02-1.0%  Calcium Carbonate  10-50%Mica 0.5-10% Attapulgite Clay 0.2-10% Talc 0.0-10% Perlite 0.0-40%Polyethylene oxide 0.0-10% Polyether siloxane 0.0-10%Microcrystalline-wax emulsion 0.1-20% Latex binder 0.5-10% Celluloseether thickener 0.1-8.0% 

Further, an example of a specific formulation for alow-dust/water-resistant joint compound can is shown in the below Table5, although other weight percentages may be used:

TABLE 5 Example Composition of a Low-Dust Joint Compound Compound Wt. %Preservative 0.01 Wetting Agent 0.05 Latex Binder 5.89 Water 34.60Microcrystalline-wax emulsion 7.36 Cellulose ether 0.55 Attapulgite clay1.84 Mica 7.36 Calcium Carbonate 33.86 Expanded Perlite 8.47

Another embodiment of a low-dust/water-resistant ready-mix jointcompound formula is shown in the below Table 5. In this embodiment, anoptional potassium siliconate additive is incorporated.

TABLE 6 Embodiment of Low-Dust Joint Compound Composition Raw MaterialWt. % Preservative 0.20% Latex (CPS 716) 6.50% Water 36.70%Microcrystalline-Wax Emulsion 3.80% Potassium Siliconate (Silres BS 16)0.20% Cellulose Ether 0.60% Clay (Attagel 30) 1.90% Mica 6.10% Limestone(MW 100) 35.20% SilCel 43-34 8.80%Low-Dust Joint Compounds-Comparative Examples

To assess the reduction of dust formation during the sanding process bysamples created with joint compound compositions of the presentinvention, the samples were compared with three other commerciallyavailable products. Testing was performed on all products upon thoroughmixing. The commercially available products compared herein were:

-   -   (1) LaFarge North America, Inc.'s (“LaFarge”) from United States        Gypsum Company's (“USG”);    -   (2) Sheetrock Lightweight All Purpose Plus 3 with Dust Control        from USG; and    -   (3) ProForm DustTech from National Gypsum Company (“NSG”).        Test Procedure

A test chamber was constructed as described at Col. 6, Lines 26-56 inU.S. Pat. No. 6,358,309, which is incorporated by reference herein. Apower sander made by Makita Corporation, model B04556 was used to sandthe specimens. The peak or highest level of dust particles measured foreach sample was recorded. (See U.S. Pat. App. Pub. No. 20110065839).

The test procedure for measuring the quantity of airborne particlesgenerated when sanding the hardened joint compound was as follows.First, each test specimen was prepared according to a specificformulation. The test specimens were approximately five inches long, oneand one-half inches wide, and one quarter of an inch thick (5″×1½″×¼″).Before sanding, each test specimen was allowed to completely harden forat least twenty four hours at room temperature in an environment wherethe relative humidity generally ranged from about 25% to about 75%.

Referring to FIG. 4, there is shown the test enclosure 2 that was usedto sand the three test specimens and measure the quantity of airbornedust particles generated. The enclosure 2 was a rectangular box six feethigh, four feet wide, and two feet wide (6′×4′=2″). The top 6, bottom 8,side 10, and rear walls 12 of the enclosure 2 were constructed of wood,and the front wall 14 was constructed of transparent Plexiglas. Agenerally triangular access opening 16 located about one foot above thebottom wall 8 was provided in the front wall 14 to allow the individualconducting the test to insert her hand and arm into the enclosure andsand the specimen. The access opening 16 had a base dimension of about7½ inches and a height of about 8½ inches. A movable cover member 18 wasprovided to allow the enclosure 2 to be completely sealed when sandingwas completed. To sand the three specimens the cover 18 was arranged inits up position as shown by the solid lines in FIG. 4. When sanding wascompleted, the cover 18 was pivoted downwardly to completely cover theaccess opening 16 as shown in phantom 18′.

As shown, three specimens of joint compound were prepared on a sectionof wallboard 20 and the section of wallboard 20 was clamped to amounting block 22 arranged within the enclosure 2. When tested, thespecimens were located about twelve inches above the bottom wall 8 ofthe enclosure. Each specimen was tested individually and after eachtest, the enclosure was cleaned so that the quantity of airborne dustparticles measured less than 0.5 mg/m3. A particle counter 24 formeasuring the quantity of airborne particles was mounted in the rightside wall about forty eight inches above the center of the threespecimens.

The power palm sander included a 4½×4.375-inch pad equipped with a120-grit mesh sanding screen mounted over a 5×3½×¾ inch open,semi-rigid, non-woven, heavy duty, stripping, backing pad available fromMinnesota Mining and Manufacturing Company, St. Paul Minn. Sanding wasperformed at a sanding speed of approximately 14,000 OPM (orbits perminute) using ordinary sanding pressure. Ordinary sanding pressure isdefined as the amount of pressure typically required to sand a hardenedjoint compound. Sanding pressure, therefore, is the manual pressuretypically applied by an ordinary person when sanding a joint compound.It will be recognized that the sanding pressure can vary depending onthe hardness of the joint compound. Sanding was continued until thespecimen was completely sanded. That is, the entire thickness of thespecimen was sanded so that a generally smooth wall surface wasproduced. Care was taken to ensure that sanding was discontinued beforethe drywall itself was sanded. The amount of time required to sand eachspecimen varied depending on the hardness of the joint compound and thesanding pressure.

The quantity of airborne dust particles was measured starting from thetime sanding was initiated until several minutes after sanding wasdiscontinued. In general, the level of airborne dust was measured untilthe level decreased to less than 50% of its peak level. The quantity ofairborne dust was measured using a DUSTTRAK™ aerosol monitor model 8520available from TSI Incorporated, St. Paul, Minn. The particle countermeasures the number of particles having a size of less than or equal to10 microns. In the Examples, the peak or highest level of airborne dustmeasured during the test is presented. The test procedure for measuringthe quantity of airborne particles generated when sanding the hardenedjoint compound is largely the same as described in U.S. Pat. No.6,358,309, which is incorporated herein, by reference. In essence, atest specimen was prepared using each of the commercial products andformulations described above.

The DRA emulsion formulation is comprised of a micro-crystalline wax, anemulsifier, usually a carboxylic acid or ester that can be saponifiedvia a reaction with a base, and a stabilizer polyvinyl alcohol. Suitableemulsifiers were montan wax, rice wax, carnauba wax, and any such waxthat is composed of a mixture of acids and esters. Standalone acids fromC₅ to C₁₀₀, such as stearic acid, can also be used in place of theaforementioned natural waxes. Likewise, standalone esters of similarcarbon atom chain length can also be used.

Suitable bases include any compound that is capable of saponifying theester carboxylate group, or deprotonating the carboxylic acid proton.Suitable bases are inorganic basis such as potassium hydroxide andammonium hydroxide. Likewise, suitable organic basis are monoethanolamine, diethanol amine, ad triethanol amine.

Two emulsions were prepared for comparison with the commerciallyavailable low-dust joint compounds. The first emulsion comprised aparaffin wax based core. The second emulsion, that of the invention,comprised a microcrystalline-wax based core with the CMWBmicrostructure.

When the inventive CMWB microstructure based emulsion was used as a dustreduction additive to the joint compound, the joint compound improvedits dust reduction capability, over and above the simultaneousimprovement in adhesion, over the paraffin-wax based emulsion.

The joint compound's ability to reduce dust is measured as peak airbornedust production in mg/m³ units, and for the inventive joint compound ofthe present invention comprising the CMWB microstructure emulsion, thepeak airborne dust (PAD) number is reduced by the following percentagenumbers, depending upon the content of the CMWB microstructure-baseddust reduction additive emulsion in the joint compound 10, 15, 20, 25,30, 35, 40, 45, 50, 55, 60, 75, 80, 85%, 90% and 95%, and 98%. In someembodiments of the present invention the PAD number is reduced by apercentage residing in between a range defined by any two numbers above,including the endpoints of such range.

The wax emulsion was made by heating the emulsifier and the paraffin-waxin a vessel such that both become molten. In a separate vessel, ameasured quantity of polyvinyl alcohol was mixed with water at roomtemperature after which the mixture was heated to about 180° F. Themolten paraffin/montan mixture was then combined with the hotwater/polyvinyl alcohol mixture which, upon passing through a charlottemill, emerged as a stable wax emulsion where the polyvinyl alcohol wastethered to the paraffin surface, largely encapsulating the paraffin. Arepresentative formula of the wax emulsion is shown in Table 7.

TABLE 7 Representative Formula of CMWB Microstructure Based InventiveWax Emulsion Ingredient Content % Water 60.3 Polyvinyl alcohol 3Microcrystalline wax 33.5 Montan wax 3 Monoethanol amine 0.2 Total Wt.100 % Polyvinyl alcohol 3.0% % Paraffin 33.5%Commercial Low Dust Joint Compounds

TABLE 8 Airborne Dust Generated by Commercial Low-Dust Joint CompoundsCommercial Low Dust Average Peak Airborne Dust Joint Compound (mg/m³)LaFarge Rapid Coat 130 Sheetrock Dust Control 67 ProForm DustTech 74Joint Compound with Inventive CMWB Microstructure-Based DRA Emulsion

TABLE 9 Joint Compound Formulations and Dust Generation Experiment No. ⇒Control 1 2 3 4 0% CMWB 2% CMWB 3.1% CMWB 4.7% CMWB 6.2% CMWB Ingredientmicrostructure microstructure microstructure microstructuremicrostructure

DRA emulsion DRA emulsion DRA emulsion DRA emulsion DRA emulsionPreservatives 0.2 0.2 0.2 0.2 0.2 Polyether siloxane 0.1 0.1 0.1 0.1 0.1copolymer Latex CPS 716 7.5 5.2 5.1 4.3 3.5 Water 37.9 38.1 37.6 37.337.0 Wax emulsion 0.0 2.0 3.1 4.7 6.2 Cellulose ether 0.6 0.6 0.6 0.60.6 Attagel 30 clay 2.0 2.0 2.0 1.9 1.9 Mica 4K 6.3 6.3 6.3 6.2 6.2Microwhite 100 36.3 36.5 36.1 35.8 35.5 calcium carbonate Perlite,SilCel 43-34 9.1 9.1 9.0 8.9 8.9 Peak Airborne Dust 104 50 34 23 20(mg/m³)

Five wax emulsions including one Control emulsion were prepared. TheControl emulsion had 0% inventive emulsion comprising CMWBmicrostructures. Experiment 1 had 2%; Experiment 2 had 3.1%; Experiment3 had 4.7%; and Experiment 4 had 6.2% wax emulsion included in the jointcompound.

The Control sample generated approximately 104 mg/m³ of peak airbornedust. With the addition of CMWB microstructure based inventivecomposition of the present invention, the peak airborne dust (PAD)production was reduced from 104 mg/m³ to about 20 mg/m³, for the 6%concentration of the CMWB emulsion as percentage of the joint compoundweight. Even a mere 2% CMWB emulsion was able to reduce the PADproduction from 104 mg/m³ to 50 mg/m³, which is a significantimprovement in PAD generation. The commercial low dust compound LaFargehas a peak dust production number of 130 mg/m³. Thus, at a 6% inclusionof CMWB, the peak airborne dust production was reduced by 85%.Similarly, the commercial low dust compounds Sheetrock Dust has a peakdust production 67 mg/m³ and ProForm DustTech has a PAD production of 74mg/m³. Thus, at 6% inclusion of CMWB emulsion the PAD production wasreduced by about 47% and 73%.

The comparative improvement in the PAD numbers at variety of CMWBmicrostructure based emulsions is provided in Table 9.1 below:

TABLE 9.1 PAD value Improvement in of the Inventive Composition overCommercial Products Inventive Joint Inventive Joint Inventive JointInventive Joint Inventive Joint Compound Compound Compound CompoundCompound CMWB CMWB CMWB CMWB CMWB Comparative based DRA based DRA basedDRA based DRA based DRA Commercial Low emulsion emulsion emulsionemulsion emulsion Dust Compound content 0% content 2% content 3.1%content 4.7% content 6.2% LaFarge Rapid Coat  20% 61% 74% 82% 85% (130mg/m3) Sheetrock Dust −36% 25% 49% 66% 70% Control (67 mg/m3) ProFormDustTech −40% 32% 54% 69% 73% (74 mg/m3)

Thus, the CMWB microstructure based DRA emulsion based joint compoundshowed a significant and surprising peak airborne dust reductioncompared to the control as well as the commercially available compounds.

Comparison of the CMWB Based DRA and Paraffin-Based DRA

In the next step, the paraffin-wax based microstructures were used toprepare the DRA emulsion. Such DRA emulsion was added to the jointcompound in the same manner as described previously for the CMWB baseddust reduction additive. The dust reduction additives prepared from thetwo waxes were added separately to joint compounds for testing. The CMWB(microcrystalline wax-based) joint compound showed reduced PAD valuescompared to the paraffin-wax based dust reduction additive in the jointcompound (See FIG. 5).

The chart in FIG. 5 shows that at equivalent dosage (3.1%),microcrystalline-wax based emulsion as dust reduction additive in ajoint compound is more effective at reducing dust than paraffin-waxbased emulsion. The control joint compound sample which did not containany PVOH stabilized wax emulsion, recorded a peak dust particle weightof 104 mg/m³, upon sanding. The joint compound containingPVOH-stabilized paraffin-wax joint compound recorded a peak of 51 mg/m³,while the PVOH-stabilized microcrystalline-wax joint compound recorded apeak of 34 mg/m³, a 33% dust reduction efficiency over the paraffin-waxemulsion based dust reduction additive.

It is speculated that the largely amorphous nature of microcrystallinewax (it has very little crystalline content) translates into greaterflexibility of the wax, which in turn enables it to stretch and be moreefficiently distributed across a larger cross-sectional area duringsanding. This greater coverage then enables the microcrystalline wax toattach onto fine particles across a wider area, causing more of them todrop rather than become airborne. In contrast, paraffin-wax is largelycrystalline and therefore brittle. Its lack of flexibility restricts thecross-sectional area it is able to cover when sanding occurs, limitingits low dusting efficiency.

TABLE 9.2 Inventive Joint Inventive Joint Compound paraffin- ComparativeCompound CMWB based wax based DRA Commercial Low DRA emulsion contentemulsion content Dust Compound 3.1% (34 mg/m³) 3.1% (51 mg/m³) LaFargeRapid Coat 74% 61% (130 mg/m³) Sheetrock Dust 49% 24% Control (67 mg/m³)ProForm DustTech 54% 31%% (74 mg/m³)

The CMWB microstructure based DRA emulsion that was created in themanner described in this work is comprised of a microcrystalline-waxparticle that is surrounded by polyvinyl alcohol polymer chains that arechemically bound (via hydrogen bonding) to the surface of themicrocrystalline-wax. The microcrystalline-wax is therefore largelyencapsulated by polyvinyl alcohol. Stated differently, there is nosubstantially exposed microcrystalline-wax surface in this wax emulsion.The net effect of this is that, when added as a component of a jointcompound formulation, this wax emulsion augments the low-dust characteras well as adhesion and therefore necessitates the reduction in theformulation's overall binder content. Similarly, the paraffin-wax basedDRA emulsion that was created in the manner described in this work iscomprised of a paraffin-wax particle that is surrounded by polyvinylalcohol polymer chains that are chemically bound (via hydrogen bonding)to the surface of the paraffin-wax. The paraffin-wax is thereforelargely encapsulated by polyvinyl alcohol. Stated differently, there isno substantially exposed paraffin-wax surface in this wax emulsion. Thenet effect of this is that, when added as a component of a jointcompound formulation, this paraffin-wax emulsion augments the low-dustcharacter, water-resistance, as well as adhesion and thereforenecessitates the reduction in the formulation's overall binder content.

In some embodiments, the disclosed joint compound can cover a joint orhole and provide dust reduction. Further, the joint compound isformulated to properly adhere to any boards that the compound is placedonto. With regards to adhesion, embodiments of the joint compound canhave at least about 90%, 95%, 99%, or 100% bond according to an ASTMC474 peel test, hereby incorporated by reference in its entirety.Further, the joint compound can have adequate sag resistance,compatibility, and contact angle.

In some embodiments, the joint compound can provide water repellency.One indication of water repellency is the contact angle of a waterdroplet on the surface of the dried joint compound. A water dropletsurface that has a contact angle of less than 90 degrees would generallybe considered hydrophilic (the smaller the contact angle the greater thehydrophilicity). Conversely, surfaces that cause a water droplet to havea contact angle greater than 90 degrees are generally consideredhydrophobic. Commercially available ready mix joint compound havecontact angles of about zero degrees, meaning that a drop of waterplaced on such a surface will rapidly spread and wet out on the surface.Embodiments of the disclosed joint compound can have a contact anglegreater than about 60, 70, 80, 90, 100, 110, 120, or 130. In someembodiments, the joint compound can have a contact angle between about60 and 130, about 115 and 130, or about 118-120. Embodiments of thedisclosed joint compound, containing a wax emulsion, can have an averagecontact angle of about 98 degrees (based on an average of sixmeasurements), or greater than about 98 degrees, indicating ahydrophobic surface.

In some embodiments, the contact angle can be between about 60 to about110 degrees, or about 60, about 70, about 80, about 90, about 100, orabout 110 degrees.

In some embodiments, the contact angel can be any number selected fromthe following numbers in degrees:

60, 61, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78,79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96,97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111,112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125,126, 127, 128, 129, and 130.Low-Dust Products

Embodiments of the disclosed wax emulsion can be used to form manydifferent low-dust. For example, embodiments of the wax emulsion can beincorporated into building materials such as asphalt (e.g., comprising aviscous liquid or semi-solid form of petroleum), concrete (e.g.,comprising aggregate or filler, cement, water, various chemical and/ormineral admixtures, etc.), stucco, cement (e.g., formed from orcomprising calcium carbonate, clay, gypsum, fly ash, ground granulatedblast furnace slag, lime and/or other alkalis, air entrainers,retarders, and/or coloring agents) or other binders. In someembodiments, the wax emulsion can be incorporated into concrete covercoat formulations, such as those used for filling, smoothing, and/orfinishing interior concrete surfaces, drywall tape, bead embedment,skim-coating, and texturing drywall. Further, embodiments of the waxemulsion can be incorporated into concrete and/or cement mixtures as adust reducing additive. Therefore, embodiments of the wax emulsion canbe incorporated into pourable concrete and/or cement that can be used,for example, for foundations in home constructions. Additionally,embodiments of the wax emulsion can be used in cinder blocks as well asother similar concrete or cement based products. In some embodiments, alow-dust building material can be formed with cement, wax emulsion, andsilicone, or siloxane, or siliconate, or fluorinated compound, orstearate, or combinations thereof.

Embodiments of the wax emulsion can also be incorporated into boards,such as cement boards (e.g., a relatively thin board, comprising cementbonded particle boards and cement fiber (e.g., comprising cement,fillers, cellulose, mica, etc.), which may be 0.25-0.5 inch thick orwhich may be thicker or thinner), and/or cement board formulations.Therefore, the wax emulsion can be used to provide additional dustreduction/of the boards, and.

From the foregoing description, it will be appreciated that inventivedevices and approaches for low-dust/and wax emulsions have beendisclosed. While several components, techniques and aspects have beendescribed with a certain degree of particularity, it is manifest thatmany changes can be made in the specific designs, constructions andmethodology herein above described without departing from the spirit andscope of this disclosure.

Certain features that are described in this disclosure in the context ofseparate implementations can also be implemented in combination as wellas in a single implementation. Conversely, various features that aredescribed in the context of a single implementation can also beimplemented in multiple implementations separately or in any suitablesub-combination. Moreover, although features may be described above asacting in certain combinations, one or more features from a claimedcombination can, in some cases, be excised from the combination, and thecombination may be claimed as any sub-combination or variation of anysubcombination.

Moreover, while methods may be depicted in the drawings or described inthe specification in a particular order, such methods need not beperformed in the particular order shown or in sequential order, and thatall methods need not be performed, to achieve desirable results. Othermethods that are not depicted or described can be incorporated in theexample methods and processes. For example, one or more additionalmethods can be performed before, after, simultaneously, or between anyof the described methods. Further, the methods may be rearranged orreordered in other implementations. Also, the separation of varioussystem components in the implementations described above should not beunderstood as requiring such separation in all implementations, and itshould be understood that the described components and systems cangenerally be integrated together in a single product or packaged intomultiple products. Additionally, other implementations are within thescope of this disclosure.

Conditional language, such as “can,” “could,” “might,” or “may,” unlessspecifically stated otherwise, or otherwise understood within thecontext as used, is generally intended to convey that certainembodiments include or do not include certain features, elements, and/orsteps. Thus, such conditional language is not generally intended toimply that features, elements, and/or steps are in any way required forone or more embodiments.

Conjunctive language such as the phrase “at least one of X, Y, and Z,”unless specifically stated otherwise, is otherwise understood with thecontext as used in general to convey that an item, term, etc. may beeither X, Y, or Z. Thus, such conjunctive language is not generallyintended to imply that certain embodiments require the presence of atleast one of X, at least one of Y, and at least one of Z.

Language of degree used herein, such as the terms “approximately,”“about,” “generally,” and “substantially” as used herein represent avalue, amount, or characteristic close to the stated value, amount, orcharacteristic that still performs a desired function or achieves adesired result. For example, the terms “approximately”, “about”,“generally,” and “substantially” may refer to an amount that is withinless than or equal to 10% of, within less than or equal to 5% of, withinless than or equal to 1% of, within less than or equal to 0.1% of, andwithin less than or equal to 0.01% of the stated amount.

Some embodiments have been described in connection with the accompanyingdrawings. The figures are drawn to scale, but such scale should not belimiting, since dimensions and proportions other than what are shown arecontemplated and are within the scope of the disclosed inventions.Distances, angles, etc. are merely illustrative and do not necessarilybear an exact relationship to actual dimensions and layout of thedevices illustrated. Components can be added, removed, and/orrearranged. Further, the disclosure herein of any particular feature,aspect, method, property, characteristic, quality, attribute, element,or the like in connection with various embodiments can be used in allother embodiments set forth herein. Additionally, it will be recognizedthat any methods described herein may be practiced using any devicesuitable for performing the recited steps.

While a number of embodiments and variations thereof have been describedin detail, other modifications and methods of using and medicalapplications for the same will be apparent to those of skill in the art.Accordingly, it should be understood that various applications,modifications, materials, and substitutions can be made of equivalentswithout departing from the unique and inventive disclosure herein or thescope of the claims.

What is claimed:
 1. A method of using a first low-dust¹, wall-repaircompound composition that has low-dust property, said method comprising:(I) applying said wall-repair composition to a wallboard panel; (II)allowing said wall-repair composition to dry; and (III) sanding saiddried wall-repair composition; wherein said wall-repair compositioncomprises a dust reduction additive emulsion comprisingcolloidally-protected micro-crystalline wax-based (CMWB) microstructure,wherein the CMWB microstructure comprises: (A) a wax core, wherein saidwax core comprises a micro-crystalline wax component and optionally anon-micro-crystalline wax component, wherein said micro-crystalline waxcomponent comprises at least one linear alkane wax defined by thegeneral formula C_(n)H_(2n+2), where n ranges from 13-80, wherein saidnon-micro-crystalline wax component comprises at least one wax selectedfrom the group consisting of animal-based wax, plant-based wax, mineralwax, synthetic wax, a wax containing organic acids and/or esters,anhydrides, an emulsifier containing a mixture of organic acids and/oresters, and combinations thereof; (B) a polymeric shell, wherein saidpolymeric shell comprises at least one polymer selected from the groupconsisting of polyvinyl alcohol, polyvinyl alcohol copolymers, polyvinylalcohol terpolymers, polyvinyl acetate, polyvinyl acetate copolymers,polyvinyl acetate terpolymers, cellulose ethers, polyethylene oxide,polethyleneimines, polyvinylpyrrolidone, polyvinylpyrrolidonecopolymers, polyethylene glycol, polyacrylamides andpoly(N-isopropylamides), pullulan, sodium alginate, gelatin, starches,and combinations thereof; and optionally (C) at least one compoundselected from the group consisting of a silicone, a siliconate, afluorinated compound, a stearate, or a combination thereof.
 2. Themethod as recited in claim 1, wherein said first low-dust, wall-repaircompound is a joint compound or a spackling compound.
 3. The method asrecited in claim 1, wherein the weight of said dust reduction additiveemulsion is in the range of from about 0.1% to about 20% by weight ofsaid first low-dust, wall-repair compound composition.
 4. The method asrecited in claim 3, wherein said first low-dust, wall-repair compound isa first joint compound or a first spackling compound.
 5. The method asrecited in claim 1, wherein said polymeric shell comprises polyvinylalcohol.
 6. The method as recited in claim 5, wherein said firstlow-dust, wall-repair compound is a first joint compound or a firstspackling compound.
 7. The method as recited in claim 1, wherein saiddust-reduction additive emulsion further comprises a base and adispersant.
 8. The method as recited in claim 1, wherein the silicone,siliconate, fluorinated compound, or stearate are selected from thegroup consisting of metal siliconate salts, potassium siliconate, polyhydrogen methyl siloxane, polydimethyl siloxane, stearate-based salts,and combinations thereof.
 9. The method as recited in claim 8, whereinsaid first low-dust wall-repair compound is a first joint compound or afirst spackling compound.
 10. The method as recited in claim 1, whereinthe quantity of dust generated upon sanding of said first low-dust wallrepair compound composition is reduced at least by 5% of the quantity ofdust generated upon sanding of a second wall-repair compound compositionhaving the same composition as said first low-dust, wall-repaircompound, but not comprising said dust reduction additive emulsion. 11.The method as recited in claim 10, wherein said first low-dust,wall-repair compound is a first joint compound or a first spacklingcompound; and said second wall-repair compound is a second jointcompound or a second spackling compound.
 12. The method as recited inclaim 1, wherein the quantity of dust generated upon sanding of saidfirst low-dust wall repair compound composition is reduced at least by80% of the quantity of dust generated upon sanding of a secondwall-repair compound composition having the same composition as saidfirst low-dust, wall-repair compound, but not comprising said dustreduction additive emulsion.
 13. The method as recited in claim 12,wherein said first low-dust, wall-repair compound is a first jointcompound or a first spackling compound; and said second wall-repaircompound is a second joint compound or a second spackling compound. 14.The method as recited in claim 1, wherein the quantity of dust generatedupon sanding of said first low-dust, wall-repair compound composition isreduced at least by 80% of the quantity of dust generated upon sandingof a second wall-repair compound composition having the same compositionas said first low-dust, wall-repair compound, but not comprising saiddust reduction additive emulsion.
 15. The method as recited in claim 14,wherein said first low-dust, wall-repair compound is a first jointcompound or a first spackling compound; and said second wall-repaircompound is a second joint compound or a second spackling compound. 16.A method for reducing the quantity of dust generated by awall-repair-compound composition, said method comprising the steps of:(I) providing a first wall-repair-compound composition comprising afiller, a first water, a binder, and at least one of a defoamer, wettingagent, preservative, fungicide, thickener, non-leveling agent,surfactant, and a solvent; (II) subsequently adding a sufficientquantity of a dust-reduction additive emulsion to said first wall-repaircompound composition to reduce the quantity of dust generated by sandingthe first wall-repair compound composition by at least 5% of thequantity of dust generated upon sanding of a second wall-repair compoundcomposition having the same composition as said first wall-repaircompound, but not comprising said dust reduction additive; wherein saiddust reduction additive emulsion comprises a colloidally-protectedmicro-crystalline wax-based (CMWB) microstructure, wherein the CMWBmicrostructure comprises: (A) a wax core, wherein said wax corecomprises a micro-crystalline wax component and optionally anon-micro-crystalline wax component, wherein said micro-crystalline waxcomponent comprises at least one linear alkane wax defined by thegeneral formula C_(n)H_(2n+2), where n ranges from 13-80, wherein saidnon-micro-crystalline wax component comprises at least one wax selectedfrom the group consisting of animal-based wax, plant-based wax, mineralwax, synthetic wax, a wax containing organic acids and/or esters,anhydrides, an emulsifier containing a mixture of organic acids and/oresters, and combinations thereof; and (B) a polymeric shell, whereinsaid polymeric shell comprises at least one polymer selected from thegroup consisting of polyvinyl alcohol, polyvinyl alcohol copolymers,polyvinyl alcohol terpolymers, polyvinyl acetate, polyvinyl acetatecopolymers, polyvinyl acetate terpolymers, cellulose ethers,polyethylene oxide, polethyleneimines, polyvinylpyrrolidone,polyvinylpyrrolidone copolymers, polyethylene glycol, polyacrylamidesand poly(N-isopropylamides), pullulan, sodium alginate, gelatin,starches, and combinations thereof; and optionally (C) at least onecompound selected from the group consisting of a silicone, a siliconate,a fluorinated compound, a stearate, or a combination thereof; (III)applying said first wall-repair composition to a wallboard panel; (IV)allowing said first wall-repair composition to dry; and (V) sanding saiddried composition.
 17. The method as recited in claim 16, wherein saidfirst wall-repair compound is a first joint compound or a firstspackling compound; and said second wall-repair compound is a secondjoint compound or a second spackling compound.
 18. The method for asrecited in claim 16, wherein the quantity of dust generated in thesanding step is reduced by at least 80% of the quantity of dustgenerated upon sanding of said second wall-repair compound compositionhaving the same composition as said first wall-repair compound, but notcomprising said dust reduction additive emulsion.
 19. The method asrecited in claim 18, wherein said first wall-repair compound is a firstjoint compound or a first spackling compound; and said secondwall-repair compound is a second joint compound or a second spacklingcompound.
 20. The method as recited in claim 18, wherein said firstwall-repair compound is a first joint compound or a first spacklingcompound; and said second wall-repair compound is a second jointcompound or a second spackling compound.
 21. The method as recited inclaim 12, wherein said first low-dust, wall-repair compound compositionhas a contact angle of from about 60° to about 150°; wherein said firstlow-dust, wall-repair compound composition has a Cobb value of formabout 5.0 to about 100 g/m²; or wherein said first low-dust wall-repaircompound composition has a contact angle of from about 60° to about 150°and a Cobb value of from about 5.0 to about 100 g/m².
 22. The method asrecited in claim 20, wherein said first low-dust wall-repair compound isa first joint compound or a first spackling compound.